The present invention relates to disk drives such as a hard disk.
In recent years, various kinds of devices are equipped with hard disks. For example, portable music players and car navigation systems are each equipped with a hard disk. Under the circumstances, a shingle write method is known as one of the techniques for increasing the storage capacity for information with the size of a hard disk itself being miniaturized. In this method, data is successively written to a data track with part of the data track being overwritten by an adjacent data track from the inner circumferential side to the outer circumferential side on a recording medium so that the data tracks form a pattern like shingles. As a result, it is possible to realize a data track narrower than the actual write width of a magnetic head.
However, if this method is adopted, for example, when data is written to a k-th data track (k is counted from the inner circumferential side), all data tracks from the k-th track to the outermost circumferential track must be rewritten. For this reason, in order to reduce the overhead of the rewriting, patent document 1 (U.S. Pat. No. 6,185,063) discloses the technique as described below.
To be more specific, according to the technique disclosed in patent document 1, two data tracks are treated as a group, and writing is performed for this group by the shingle write method. In other words, between the two data tracks constituting the group, writing is first performed for the data track on the inner circumferential side, and then writing is performed for the data track on the outer circumferential side. Here, part of the data track on the outer circumferential side is not overwritten. Accordingly, this data track on the outer circumferential side becomes a data track having the same width as the write width of the magnetic head.
According to this method, because a read position of an odd number data track is allowed to differ from that of an even number data track, it is possible to set a read position with overwritten part (overlapped part) of the data tracks which constitute the group being excluded (refer to FIG. 10 of patent document 1). Therefore, it is possible to rewrite data relatively flexibly.